The goal of this project is to investigate and gain a better understanding of the biochemical alterations in the pituitary leading and ultimately causing ovulation. By utilizing an in vivo isolated pituitary we plan to study the effect of LHRH and gonadal steroids, alone, and in combination treatment on various biochemical parameters. This preparation may provide experimental insight into interacting factors integral to the cyclic surge of gonadotrophins. This will be finished in three years time. The project is divided into two phases. The first eighteen months will be spent investigating the effect of LHRH and estradial-B17 on the ultrastructure of the isolated pituitary. In addition, the effect of the above treatments on levels of serum and pituitary gonadotrophins will be measured. Levels of newly synthesized RNA, and gonadotrophins will be determined. During the second half of the project, the effect of LHRH and gonadal steroids upon pituitary receptor level will be investigated. The possible role that progesterone may have on the above mentioned parameters will be determined. Information gained from the above described goals may lend insight into new approaches to contraception.